Wednesday, November 11, 2009

Some confusion with my new tires

As already mentioned before my old steed was rewarded with some new tires. So far I only had typical cross country tires (Stollenreifen, in German) on my mountain bike. These days, however, I'm mostly only cycling on the road and a flatter profile is preferable. On the other hand, with the winter in sight (and that also means snow in Vienna) I did not completely want to turn studs down.

A compromise was found and I settled for the Schwalbe Land Cruiser. That's a tough, puncture-resistant and versatile mixed surface tire. The tires have a central pattern for tarmac but also serrated side knobs for dirt roads (and hence also snow). With 15€ per tire they are quite cheap too. For more information have a look at the Schwalbe homepage.

To explain the title of this post I must admit that at first I had some trouble when mounting the tires. Well, usually the direction of wheel travel is pretty obvious from the tire pattern itself but this time I was really confused because there were two direction arrows written on the tire sidewalls, pointing in opposite directions:

What was that supposed to mean? Should the arrow point to the back of it? Or do these arrows indicate that the front and rear tires should be mounted differently? Would that make any sense?

This is how my front tire (left) and rear tire (right) are mounted now

Well, according to the explanation on the Schwalbe homepage the front and rear wheel should really be treated differently for mountain bikes. Curious as I am, I tried to find out why that makes sense. Apparently, directing the tires this way leads to better braking characteristics on muddy surfaces. I don't know if it actually makes a difference, but I'm ready to give it a go.

What kind of tires do you ride? Does anybody out there know more about the sense of differently directed front and rear tires?

12 comments:

I've pretty well always ridden a mountain bike with about 2" wide tires. I first noticed the arrows when I got a flat and needed to change tubes. Because I was in such a rush I just put it on any which way and had no issues.

Every time I get a flat (which I got one today) I just ignore the arrows. I have never had any problems so I assume they don't mean a whole helluva lot...Or I've just been lucky and have put the tire on the correct way all this time.

I love my Schwalbe Marathon tires. I just bought a second set for my new old bike. They're kevlar belted and although they're not inexpensive, they've held up really well. And I really like the reflective ring on the tires- it's very visible in headlights, and the shape is instantly identifiable as a bicycle.

I have the same problem with Tyres and the drive direction Arrows. I got a new fast Bike Recently and I was unhappy with the Smooth Clincher Tyres because of the coming Winter Weather.

It was either Oil on the Road or the Rain that Day that was making me Skid a bit and I Cycled carefully until I decided to get Winter Tyres.

I got Continental Touring Plus Tyres or Conties as some People call them. I fitted on the front Tyre and was congratulating myself on how easily they were fitting then I discovered that the Arrows were pointing the wrong way. With much Strong Language I decided to do it right and changed it around. I decided I had better get that Rear Tyre done right the first time as it is more awkward. I kept looking at the front Tyre to make sure it was on right.

Result perfect and the Tyres are running smoothly with no more slipping or skidding. I must keep some kind of Record on Longevity of the Tyres for Future reference. I never done so in the past with my other Bike Tyres. I have my Dutch Bike with Schwalbe Marathons with Kevlar Belt and still perfect after nearly 3 Years. I have a Brompton folding Bike and I got a slow Flat Tyre on the Rear wheel and had to keep Pumping it up and when I got Home I discovered that the Tyre is Split on the side Wall. This is after 7 Years and a second Puncture with ordinary Brompton Tyres. But I do not use this Bike much. So I will probably get Schwalbe Mararathons with Kevlar as it is not easy fixing Punctures on it.

My Vittoria cyclocross tires have similar notation, but the Italians are less dogmatic my arrows are called "traction" and "speed." If anyone says anything, just note that you've optimized for one or the other above. I have no idea how much difference any of this really makes, or whic YOUR tires are currently set for.

It's simple really: You want the rear wheel to "dig into the surface" when you spin the pedals ("forward" acceleration) and the front wheel to "dig in" when you squeeze the brake ("backward" acceleration). This arrangement requires opposite from normal orientations of the grippy treads on the front tyre.

Of course this makes no difference on pavement because grippy treads don't grab solid surfaces regardless of their orientation. That's why you want smooth road tyres. Or, if the treads are perfectly symmetrical, as they are on many tyres, then it doesn't matter. So, in theory, the arrow direction is only an issue if you ride on dirt (and even then, I doubt that your braking/acceleration friction coefficient is much improved by directionality of the grippy parts...)

As MDI correctly says, the tread pattern makes no difference on a hard surface. For better grip you want a smooth tyre with soft rubber, so that the not quite smooth surface of the road will penetrate the tyre. That's where the grip comes from. However, soft rubber wears out quicker than hard rubber, so there is a compromise to be made between grip and lifespan.

While the direction of tread may make a small amount of sense for off road riding, I suspect that direction arrows on road tyres are more a case of marketing (making the product sound more technical, therefore more advanced and desirable).

Directional arrows on tires serve their purpose as pointed out by MDI. Really want to have fun? Put your tractor tires on backwards and get stuck in a muddy field! Nothing like having to leave the piece of equipment and travel in reverse to the barn. I primarily travel on surfaced roads on a realitvely smooth tire, so directional treads aren't as important, however I do install the according to the tire manufacturers wishes.

Go0gled the drive arrows while mounting a pair of new schwalbe big bettys as the uni-direction markind was confusing. Found this blog on the first page of hits. Hope it's alright to drop a line!

Wanted to add that direction is more important than it may seem. It's equally important on all surfaces too. Especially noticeable during the most critical job of all; hard braking. Thread pattern is usually designed to grip well in one direction and it's designed to keep behaving well if it looses traction. A locked front wheel (a regular part of hard braking) should keep going straight. If the tire direction is reversed, the front will skid sideways on its own.

The rear wheel is usually set up in the other direction, delivering acceleration forces from the pedalling. That explains why locked rear wheels usually have a strong tendency to skid sideways, the thread is set up the wrong way for braking.

There's also an issue of side wall strength. It may be designed to cope better with forces in a certain direction.

(qualifications: 10 years motorcycling with track courses etc, 7 years full time bicycle couriering in all seasons. gone through loads of tires! have mananged to mount them the wrong way a couple of times. it usually results in a spill at the first hard braking opportunity!)

Post a Comment

About

Our blog is focused on expressing different views on cycling in everyday life across Europe. We post stories from continental Austria, nordic Finland and sunny Spain, according to our cultural and professional background. Thus a variety of personal stories and scientific issues are covered. We hope to provide a somewhat comprehensive insight in cycling culture and lifestyle in Europe. In keeping with the theme of the blog we make a point why and indeed how a bicycle is an ideal mode of transport, despite of or especially in today's bustling world.